Stored gas on-board inert gas generating systems (OBIGGS) find use in aircraft for rendering onboard fuel tanks relatively inert through introduction of a gas such as nitrogen-enriched air, thereby, potentially reducing the risk of explosion and improving safety on such aircraft. In a stored gas OBIGGS, aircraft engine bleed air and/or air from an auxiliary power unit (APU) may be supplied to an air separation module (ASM) that creates nitrogen-enriched air (NEA), while exhausting the oxygen-rich waste gas overboard. The NEA generation rate is often higher than needed by the aircraft during climbing and cruising, but significantly lower than needed during for the aircraft's descent. Therefore, the surplus NEA produced during climbing and cruising may be compressed by an on-board compressor, such as a multi-staged compressor, and stored in high pressure storage containers. The stored NEA may then be supplied to the fuel tanks at the rate generally needed for various phases of flight, such as during the aircraft's descent.
However, issues may arise in an OBIGGS in that during engine idle and APU operations, the pressure of the incoming air to the ASM may be significantly lower than the ASM's pressure regulator setting, with the NEA mass flow rate being proportionally reduced. The pressure stages in the storage compressor may not be well balanced at such lower incoming air pressures. Consequently, operation of an OBIGGS under low compressor inlet pressure conditions may result in increased compressor vibration and reduced compressor life.
Therefore, it may be desirable to have a system and method that takes into account at least some of the issues discussed above, as well as possibly other issues.